The benefits of a consistent exercise regimen have been well documented. It is now well accepted that exercising provides a number of health advantages, both in long term effects of preventing disease and in the short term effects of mental awareness, relaxation, and stress relief. It is believed that lack of exercise for an extended period of time (especially for those who are accustomed to regular exercise) can result in increased stress, reduced mental awareness, and resulting poor performance.
In some situations however, exercise can be very difficult to perform due to a lack of physical space. These situations seem to occur often during space missions, armed forces service on a vessel such as a submarine, or in a congested environment such as a small apartment in a large city.